Is an LPN the highest rank in nursing?

It primarily depends upon the degree and specialization, but as a general rule of thumb - it is. A nurse practitioner has either a Master's degree or a Doctorate degree. There are other nursing specialties that also require these degrees such as Legal Nurse Consultant, Certified Nurse Specialist, Certified Nurse Midwife, and Nurse Educator to name some. Each of these has additional responsibilities above and beyond that of a registered nurse and are comparable to a nurse practitioner other than they are in different fields and responsibilities.